As a Light-Emitting Diode (LED) capable of emitting a visible light in red color, orange color, yellow color or yellowish-green color, the compound semiconductor LED that is equipped with a light-emitting layer formed of aluminum-gallium-indium phosphide ((AlXGa1-X)YIn1-YP in which 0≦X≦1, 0<Y≦1) has been hitherto known. In the LEDs of this kind, the light-emitting part provided with a light-emitting layer formed of (AlXGa1-X)YIn1-YP; in which 0≦X≦1, 0<Y≦1, is generally formed on a substrate material, such as gallium arsenide (GaAs) which is optically impervious to the light emitted from the light-emitting layer and mechanically not so strong.
Recently, therefore, with a view to obtaining a visible LED of higher brightness and with the object of further enhancing the mechanical strength of the device, the technique for configuring a junction LED by expelling impervious substrate material, such as GaAs, and thereafter incorporating anew a support layer formed of a transparent material capable of transmitting the emitted light and as well excellent in mechanical strength more than ever has been being developed (refer, for example, to Japanese Patent No. 3230638, JP-A HEI 6-302857, JP-A 2002-246640, Japanese Patent No. 2588849 and JP-A 2001-57441).
For the purpose of fabricating a visible LED of high brightness, the method that relies on the shape of a device to attain improvement in the efficiency of light emission is being used. In the configuration of a device by having electrodes formed respectively on the first surface and on the back surface of a semiconductor light-emitting diode, for example, the technique for accomplishing the enhancement of brightness by the shape of side faces has been disclosed (refer, for example, to JP-A SHO 58-34985 and U.S. Pat. No. 6,229,160).
Though the junction LED has made it possible to provide an LED of high brightness, the need to seek an LED of yet higher brightness is still persisting. Numerous shapes have been proposed for the devices that are so configured as to have electrodes formed on the first surface and the back surface of a light-emitting diode, respectively. The device of a configuration having two electrodes formed on a light-extracting surface is complicated in shape and has not been optimized as respects the state of side faces and the disposition of the electrodes. This invention is directed toward the light-emitting diode provided on the light-extracting surface thereof with two electrodes and is aimed at providing a light-emitting diode of high brightness that exhibits a high efficiency in the extraction of light.
This invention has been produced for the purpose of solving the problem mentioned above.